CA1164248A - Stable infrared analyzer - Google Patents
Stable infrared analyzerInfo
- Publication number
- CA1164248A CA1164248A CA000385492A CA385492A CA1164248A CA 1164248 A CA1164248 A CA 1164248A CA 000385492 A CA000385492 A CA 000385492A CA 385492 A CA385492 A CA 385492A CA 1164248 A CA1164248 A CA 1164248A
- Authority
- CA
- Canada
- Prior art keywords
- sample
- signal
- peak
- comparison
- interruptor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000003321 amplification Effects 0.000 claims abstract description 5
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 5
- 239000003990 capacitor Substances 0.000 claims description 13
- 230000003595 spectral effect Effects 0.000 claims description 12
- 230000001360 synchronised effect Effects 0.000 claims description 8
- 230000005855 radiation Effects 0.000 claims description 6
- 230000003287 optical effect Effects 0.000 claims description 5
- 230000011664 signaling Effects 0.000 claims description 2
- 238000001514 detection method Methods 0.000 claims 1
- 230000015654 memory Effects 0.000 description 5
- 239000012530 fluid Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000002277 temperature effect Effects 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/37—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using pneumatic detection
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
STABLE INFRARED ANALYZER
Abstract of the Disclosure A double beam infrared analyzer is modulated to separately and alternately project the sample beam and comparison beam into a condenser microphone type detector thereby generating alternate pulsed signals indicating the intensity of the sample beam and comparison beam. The peak comparison beam signal is detected and maintained at a constant value through a feedback circuit controlling the degree of amplification of both the comparison beam signal and the sample beam signal, thereby providing comparison and sample signals that are corrected every cycle for analyzer instabilities.
Abstract of the Disclosure A double beam infrared analyzer is modulated to separately and alternately project the sample beam and comparison beam into a condenser microphone type detector thereby generating alternate pulsed signals indicating the intensity of the sample beam and comparison beam. The peak comparison beam signal is detected and maintained at a constant value through a feedback circuit controlling the degree of amplification of both the comparison beam signal and the sample beam signal, thereby providing comparison and sample signals that are corrected every cycle for analyzer instabilities.
Description
Field of the Invention This invention relates to double beam infrared fluid analyzers using pneumatic detectors oE the condenser microphone type, and more particularly to an improved analyæer having exceptional stability against error resulting from analyzer instabilities. Such errors may result from changes in ambient temperature, changes in the intensity of the infrared energy source, or instabilities in the pneumatic detector or the associated preamplifier and amplifier.
2~ ~ack~round of the Invention In the conventional double beam analyzer with pneumatic detectors, one beam passes through the fluid sample to be ànalyæed and is atten-nuated because of absorption of infrared energy in a given spectral ran~e by the presence of the component to be determined; the second beam of substantially equal intensity passes through a comparison fluid, normally substantially nonabsorbent in the measured spectral range of absorbence by the component to be determined. In Waters, U. S. Patent No. 2,648,775, the two beams are modulated by an interrupter to separa-tely .' ' ~ ~ . .
~ ~ 6~
and alternately project the two beams at a rapid frequency into a condenser microphone type detector responsive to the intensity of the beams in the spectral region of interest.
The concentration of the fluid to be determined is indicated by the magnitude of the signal difference resulting from the two beams. Although the purpose of the high-frequency alternation was to avoid temperature effects between succes-sive cycles, the instrument had no provision for correcting errors resulting from slower changes in ambient conditions and other instrument instabilities.
Summary of the Invention An object of an aspect of this invention is to provide a double beam infrared analyzer of enhanced stability. An object of an aspect of this invention is to provide such an analyzer in which the peak signal derived from the comparison beam is automatically maintained at a predetermined level and in which the comparison beam signal and sample beam signal are equally amplified. Other objects will be apparent from the following description and claims.
An aspect of the invention is as follows :
An infrared analyzer of the type in which the radiation travels along two beam paths, one a sample beam path traversing a gas sample to be analyzed, the other a ~5 comparison beam path traversing a reference gas sample, wherein the presence of the component to be determined in the gas sample affects the relative intensity of the beams in a spectral region, the analyzer comprising a detector of the condenser microphone type responsive to changes in the beam intensity in the spectral region, means to cyclically modulate both beams such that in one portion of each cycle the sample beam is interrupted while the reference beam is not interrupted and in another but non-consecutive portion of each cycle the reference beam is interrupted while the sample beam is not, the non-consecutive cycle portions being separated by an intervening cycle portion in which both beams are simultaneously interrupted or simultaneously not interrupted, whereby the detector generates a series of alternate pulsed signals indicating the intensity of the reference beam and sample beam respectively, means to amplify the pulsed signals, means to store the peak value of the amplified comparison signal, feedback means responsive to the amplified comparison signal and control-ling the magnitude of amplification to provide a predetermined peak amplitude of the comparison signal, and means to measure the difference between the peak comparison signal and the peak sample signal.
The invention is an improvement to infrared analyzers of the type in which the infrared radiation travels along two beam paths, one a sample beam path trav-ersing a gas sample to be analyzed, the other a reference beam traversing a reference gas sample, wherein the presence of ~he component to be determined in the gas sample, affects the relative intensity of the beams in a spectral region, and wherein the two beams are cyclically modulated by an interrupter to be separately and alternately received by a detector of the condenser microphone type responsive to changes in beam intensity in the said spectral region.
The detector generates a series of pulsed si~nals and the magnitude of alternate pulsed signals indicate the 6~ a intensity of the detected sample beam and reference beam respectively.
The peak comparison signal is segregated and maintained at a constant value through a feed back circuit, correcting the comparison signal for analyzer instabilities, and the feed-back circuit controls -2b-, ~ ~6~2~
the degree of amplification of both the comparison signal and the sample signal. Thus the comparison and sample signals are corrected every cycle for instabilities.
srief Description of the Drawings Fig. 1 is a partial diagrammatic illustration of embodiment of this invention showing the interruptor in relation to the infrared beam.
Fig. 2 is a partial diagram of the analyzer of Fig. 1, showing the interruptor in relation to a timing pulse generator.
Fig. 3 is a diagram of the signal waveform generated by the analyzer detector.
Fig. 4 is a diagram of c~clical interruption positions coordinated with Fig. 2.
Description of the Preferred Embodiment The presently preferred embcdiment is described with reference to Fig. 1, Fig. 2, Fig. 3 and Fig. 4. Infrared sources 2 and 4, for the sample beam and cQmparison beam respectively, are intersected by a 90 segment, pie-shaped interruptor 6, opaque at least in the spectral region of interest, rotated at a speed of about 2 cps by synchronous motor 8.
Each beam is provided with conventional trimmer screw 10 to adjust the intensity of the beam. The sample beam passes through a sample cell 12, which is provided with a sample inlet 14 and outlet 16 and is otherwise sealed by windows 18, transparent to infrared radiation. The sample beam then enters the chamber 20 of pneumatic detector 22. l`he comparison beam follows a parallel path through the interruptor region and comparison cell 24, similar to the sample cell except that it contains a fixed volume of reference gas, usually like the sample gas but without the camponent that is to be measured. m e comparison beam then enters chamber 26 of the detector.
The chambers 20 and 26 and the interconnecting passage, delineated by diaphragm 28 of a condensor microphone are filled with a gas which absorbs radiation in the same spectral region as the gas being measured, , .
usually the same gas. The gas warms and expands as radiation is ab-sorbed causing the diaphragm to move. The movement of the diaphragm in relation to plate 30 generates a capacitance output signal.
In operation, the interruptor 6 modulates both beams to produce a signal from the pneumatic detector having the wave form showin in Fig.
~ ~ 6~
and alternately project the two beams at a rapid frequency into a condenser microphone type detector responsive to the intensity of the beams in the spectral region of interest.
The concentration of the fluid to be determined is indicated by the magnitude of the signal difference resulting from the two beams. Although the purpose of the high-frequency alternation was to avoid temperature effects between succes-sive cycles, the instrument had no provision for correcting errors resulting from slower changes in ambient conditions and other instrument instabilities.
Summary of the Invention An object of an aspect of this invention is to provide a double beam infrared analyzer of enhanced stability. An object of an aspect of this invention is to provide such an analyzer in which the peak signal derived from the comparison beam is automatically maintained at a predetermined level and in which the comparison beam signal and sample beam signal are equally amplified. Other objects will be apparent from the following description and claims.
An aspect of the invention is as follows :
An infrared analyzer of the type in which the radiation travels along two beam paths, one a sample beam path traversing a gas sample to be analyzed, the other a ~5 comparison beam path traversing a reference gas sample, wherein the presence of the component to be determined in the gas sample affects the relative intensity of the beams in a spectral region, the analyzer comprising a detector of the condenser microphone type responsive to changes in the beam intensity in the spectral region, means to cyclically modulate both beams such that in one portion of each cycle the sample beam is interrupted while the reference beam is not interrupted and in another but non-consecutive portion of each cycle the reference beam is interrupted while the sample beam is not, the non-consecutive cycle portions being separated by an intervening cycle portion in which both beams are simultaneously interrupted or simultaneously not interrupted, whereby the detector generates a series of alternate pulsed signals indicating the intensity of the reference beam and sample beam respectively, means to amplify the pulsed signals, means to store the peak value of the amplified comparison signal, feedback means responsive to the amplified comparison signal and control-ling the magnitude of amplification to provide a predetermined peak amplitude of the comparison signal, and means to measure the difference between the peak comparison signal and the peak sample signal.
The invention is an improvement to infrared analyzers of the type in which the infrared radiation travels along two beam paths, one a sample beam path trav-ersing a gas sample to be analyzed, the other a reference beam traversing a reference gas sample, wherein the presence of ~he component to be determined in the gas sample, affects the relative intensity of the beams in a spectral region, and wherein the two beams are cyclically modulated by an interrupter to be separately and alternately received by a detector of the condenser microphone type responsive to changes in beam intensity in the said spectral region.
The detector generates a series of pulsed si~nals and the magnitude of alternate pulsed signals indicate the 6~ a intensity of the detected sample beam and reference beam respectively.
The peak comparison signal is segregated and maintained at a constant value through a feed back circuit, correcting the comparison signal for analyzer instabilities, and the feed-back circuit controls -2b-, ~ ~6~2~
the degree of amplification of both the comparison signal and the sample signal. Thus the comparison and sample signals are corrected every cycle for instabilities.
srief Description of the Drawings Fig. 1 is a partial diagrammatic illustration of embodiment of this invention showing the interruptor in relation to the infrared beam.
Fig. 2 is a partial diagram of the analyzer of Fig. 1, showing the interruptor in relation to a timing pulse generator.
Fig. 3 is a diagram of the signal waveform generated by the analyzer detector.
Fig. 4 is a diagram of c~clical interruption positions coordinated with Fig. 2.
Description of the Preferred Embodiment The presently preferred embcdiment is described with reference to Fig. 1, Fig. 2, Fig. 3 and Fig. 4. Infrared sources 2 and 4, for the sample beam and cQmparison beam respectively, are intersected by a 90 segment, pie-shaped interruptor 6, opaque at least in the spectral region of interest, rotated at a speed of about 2 cps by synchronous motor 8.
Each beam is provided with conventional trimmer screw 10 to adjust the intensity of the beam. The sample beam passes through a sample cell 12, which is provided with a sample inlet 14 and outlet 16 and is otherwise sealed by windows 18, transparent to infrared radiation. The sample beam then enters the chamber 20 of pneumatic detector 22. l`he comparison beam follows a parallel path through the interruptor region and comparison cell 24, similar to the sample cell except that it contains a fixed volume of reference gas, usually like the sample gas but without the camponent that is to be measured. m e comparison beam then enters chamber 26 of the detector.
The chambers 20 and 26 and the interconnecting passage, delineated by diaphragm 28 of a condensor microphone are filled with a gas which absorbs radiation in the same spectral region as the gas being measured, , .
usually the same gas. The gas warms and expands as radiation is ab-sorbed causing the diaphragm to move. The movement of the diaphragm in relation to plate 30 generates a capacitance output signal.
In operation, the interruptor 6 modulates both beams to produce a signal from the pneumatic detector having the wave form showin in Fig.
3. When the interruptor is in the position shown in position A of Fig.
4, with neither beam interrupted, the signal is a null signal shown at point A of Fig. 3. At position B of Fig. 4 the interruptor completely interrupts the comparison beam, giving the peak signal from the sample beam at point B of Fig. 3. In position C of Fig. 4, the output signal is again at a null balance shown at point C of Fig. 3. With the interruptor in position D of Fig. 4, blocking the sample beam, the peak comparison beam signal is obtained at point D of Fig. 3. This type of interruption, which in effect permits the analyzer to function alternately as a single beam sample analyæer and a single beam reference analyzer, was used by Freilino U. S. Patent 3,731,092 for the purpose of obtaining increased detector sensitivity using a flow responsive detector. Equivalent results may be obtained with other interruptors, e.g. an opaque disc having a transparent pie-shaped segment, or reciprocating shutters, it ~ being required only that there be identifiable cycle positions in which the sample beam is entirely suppressed, in which the comparison beam is entirely suppressed and that these cycle portions are non-consecutive and are seyarated by an intervening cycle portion in which both beams are modulated the same way, thereby generating alternating pulse signals indicating the intensity of the reference beam and sample beams, providing positions in the wave form equivalent to A, B, C. and D of Fig. 3.
I~ith further reference to Figs. 1 ~ 2, which schematically illus-trate the main elements of the signal treating portion of the analyzer incorporated in conventional supporting circuitry, the capacitance output signal from the detector is amplified and converted to a voltage signal by preamplifier-transducer34, which voltage signal amplitude is ad;usted by attenuator 36, and amplified by operational amplifier 38.
3. ~
The peak detector comprises a diode 40, preventing back current flow, a capacitor 42 in which the peak voltage is stored and three normally open switches, 44, 46 and 48, synchronized by electronic timers 50, 52 and 54 with the interruptor 6. The switches are preferrably optical couplers which close momentarily on receiving a timer pulse.
The timers are clocked by the 50-60 H~ line supply that also supplies the synchronous motor driving the interruptor, and are reset by a pulse via lead 55 from phototransistor 56, generated when the photransistor is blocked from LED 58 by the interruptor when the interruptor is in the position A (Fig. 4).
The reset pulse momentarily closes switch 44, discharging capacitor 42, and resets the timers 50, 52 and 54. Switch 44 reopens and, as the :lnterrupter rotates~ generating the signal waveform shown in Fig. 2, the peak sample signal at point B is stored on capacitor ~2. At a time just Eollowing the peak, point E, Timer 52 produces a pulse momentarily closing switch 46, transferring the peak signal from high impedance amplifier 45 to operational amplifier 60 and capacitor 61, serving as a sample peak signal memory. ~t point C, timer 52 generates a pulse momentarily closing switch 44 to again discharge capacitor 42. The capacitor then stores the peak comparison signal and, at a time follow~
ing the peak (point F), the timer 54 generates a pulse momentarily closing switch 48, transferring the peak comparison signal for storage by operational amplifier 62 and capacitor 63 serving as a comparison memory .
The output of operational amplifier 62 is connected as the input to feedback amplifier 64, which is referenced against a voltage 66. The output of t`he feed back amplifier is connected to control attenuator 36, which preferrably includes an optical coupler operating in a linear mode to adjust the attenuator proportionally to the output of the feedbac~
amplifier.
The output of sample memory 60 and comparison memory 62 are con-nected to differential amplifier 68, the output of which is connec-ted to a readout meter 70. The meter indicates the difference in signal 6 ~
amplitude of the sample and comparison memories. This difference is proportional to the sample concentration in the sample cell.
The purpose of the feedback network is to correct for changes within the system by maintaining the comparison signal at a constant value. If the comparison signal does vary and the signal is less than the reference voltage, the feedback amplifier controls the attenuator to increase the amplitude of the signal. Likewise, if the comparison signal is larger than the reference voltage, the Eeedback amplifier controls the attenuator to decrease the amplitude of the incoming signal. The attenuator controls the amplification of both the compar-ison and sample signals, so both signals are equally amplified. By performing this level correction in signal, changes in signal level due to instabilities in the infrared detector, preamplifier or amplifier are corrected and the stability of the analyzer is enhanced.
I~ith further reference to Figs. 1 ~ 2, which schematically illus-trate the main elements of the signal treating portion of the analyzer incorporated in conventional supporting circuitry, the capacitance output signal from the detector is amplified and converted to a voltage signal by preamplifier-transducer34, which voltage signal amplitude is ad;usted by attenuator 36, and amplified by operational amplifier 38.
3. ~
The peak detector comprises a diode 40, preventing back current flow, a capacitor 42 in which the peak voltage is stored and three normally open switches, 44, 46 and 48, synchronized by electronic timers 50, 52 and 54 with the interruptor 6. The switches are preferrably optical couplers which close momentarily on receiving a timer pulse.
The timers are clocked by the 50-60 H~ line supply that also supplies the synchronous motor driving the interruptor, and are reset by a pulse via lead 55 from phototransistor 56, generated when the photransistor is blocked from LED 58 by the interruptor when the interruptor is in the position A (Fig. 4).
The reset pulse momentarily closes switch 44, discharging capacitor 42, and resets the timers 50, 52 and 54. Switch 44 reopens and, as the :lnterrupter rotates~ generating the signal waveform shown in Fig. 2, the peak sample signal at point B is stored on capacitor ~2. At a time just Eollowing the peak, point E, Timer 52 produces a pulse momentarily closing switch 46, transferring the peak signal from high impedance amplifier 45 to operational amplifier 60 and capacitor 61, serving as a sample peak signal memory. ~t point C, timer 52 generates a pulse momentarily closing switch 44 to again discharge capacitor 42. The capacitor then stores the peak comparison signal and, at a time follow~
ing the peak (point F), the timer 54 generates a pulse momentarily closing switch 48, transferring the peak comparison signal for storage by operational amplifier 62 and capacitor 63 serving as a comparison memory .
The output of operational amplifier 62 is connected as the input to feedback amplifier 64, which is referenced against a voltage 66. The output of t`he feed back amplifier is connected to control attenuator 36, which preferrably includes an optical coupler operating in a linear mode to adjust the attenuator proportionally to the output of the feedbac~
amplifier.
The output of sample memory 60 and comparison memory 62 are con-nected to differential amplifier 68, the output of which is connec-ted to a readout meter 70. The meter indicates the difference in signal 6 ~
amplitude of the sample and comparison memories. This difference is proportional to the sample concentration in the sample cell.
The purpose of the feedback network is to correct for changes within the system by maintaining the comparison signal at a constant value. If the comparison signal does vary and the signal is less than the reference voltage, the feedback amplifier controls the attenuator to increase the amplitude of the signal. Likewise, if the comparison signal is larger than the reference voltage, the Eeedback amplifier controls the attenuator to decrease the amplitude of the incoming signal. The attenuator controls the amplification of both the compar-ison and sample signals, so both signals are equally amplified. By performing this level correction in signal, changes in signal level due to instabilities in the infrared detector, preamplifier or amplifier are corrected and the stability of the analyzer is enhanced.
Claims (7)
1. An infrared analyzer of the type in which the radiation travels along two beam paths, one a sample beam path traversing a gas sample to be analyzed, the other a comparison beam path traversing a reference gas sample, wherein the presence of the component to be determined in the gas sample affects the relative intensity of the beams in a spectral region, the analyzer comprising a detector of the condeser microphone type respon-sive to changes in the beam intensity in the spectral region, means to cyclically modulate both beams such that in one portion of each cycle the sample beam is interrupted while the reference beam is not interrupted and in another but non-consecutive portion of each cycle the reference beam is interrupted while the sample beam is not, the non-consecutive cycle portions being separated by an intervening cycle portion in which both beams are simultaneously interrupted or simultaneously not interrupted, whereby the detector generates a series of alternate pulsed signals indi-cating the intensity of the reference beam and sample beam respectively, means to amplify the pulsed signals, means to store the peak value of the amplified comparison signal and controlling the magnitude of amplification to provide a predetermined peak amplitude of the comparison signal, and means to measure the difference between the peak comparison signal and the peak sample signal.
2. An analyzer according to claim 1 in which the cyclically modula-ting means comprises a rotating interruptor having a section of about 90° opaque to the spectral region of interest.
3. An analyzer according to claim 1 having a peak detection circuit comprising a capacitor to store peak signals and a first switching means synchronized with the cyclically modulating means to discharge the capa-citor during each intervening cycle portion.
4. An analyzer according to claim 3 having a second switching means synchronized with the cyclically modulating means to momentarily connect the capacitor to a first signal storage means after the peak sample signal is stored in the capacitor and before it is discharged, and having a third switching means synchronized with the cyclically modulating means to momen-tarily connect the capacitor to a second signal storage means after the peak comparison signal is stored in the capacitor and before it is dis-charged by the first switching means.
5. An analyzer according to claim 4 comprising a feedback amplifier having a reference voltage input and a voltage input from said second signal storage means, the output of the feed back amplifier being pro-portional to the difference between the voltage input, an optical coupler attenuator connected to attenuate the sample signal and comparison signal, the output of the feedback amplifier connected to the attenuator to ad-just the attenuation inversely proportionately to the feedback amplifier output.
6. An analyzer according to claim 3 having a synchronous motor and an electronic timer to produce an electronic pulse at a predetermined time after reset connected to a common alternating current power source, a rotating interruptor driven by the synchronous motor, a time reset means activated by a predetermined angular position of the interruptor, and an optical coupler switch momentarily closing the response to the timer pulse.
7. An apparatus according to claim 4 comprising a first, second and third timer, each generating an electronic pulse at a different prede-termined time after reset; a rotating interruptor; timer reset means activated by a predetermined angular position of the interruptor; a first, second and third optical coupler switch momentarily closing in response to the first second and third timer pulse respectively.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/188,982 US4355234A (en) | 1980-09-19 | 1980-09-19 | Stable infrared analyzer |
| US188,982 | 1980-09-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1164248A true CA1164248A (en) | 1984-03-27 |
Family
ID=22695395
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000385492A Expired CA1164248A (en) | 1980-09-19 | 1981-09-09 | Stable infrared analyzer |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US4355234A (en) |
| JP (1) | JPS5779438A (en) |
| CA (1) | CA1164248A (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60198435A (en) * | 1984-03-22 | 1985-10-07 | Shimadzu Corp | Ir gas analyzer |
| IL90744A (en) * | 1989-06-25 | 1992-07-15 | Spegas Ind Ltd | Method and apparatus for gas analysis |
| US5340987A (en) * | 1991-03-15 | 1994-08-23 | Li-Cor, Inc. | Apparatus and method for analyzing gas |
| US5332901A (en) * | 1991-03-15 | 1994-07-26 | Li-Cor, Inc. | Gas analyzing apparatus and method for simultaneous measurement of carbon dioxide and water |
| JP3041827B2 (en) * | 1995-05-29 | 2000-05-15 | 株式会社島津製作所 | Infrared gas analyzer |
| US5977546A (en) * | 1997-05-13 | 1999-11-02 | Carlson; Lee Richard | Self normalizing radiant energy monitor and apparatus for gain independent material quantity measurements |
| US6201245B1 (en) | 1998-06-18 | 2001-03-13 | Robert J. Schrader | Infrared, multiple gas analyzer and methods for gas analysis |
| US6628396B1 (en) * | 1999-06-11 | 2003-09-30 | Mamac Systems, Inc. | Photo expansion gas detector |
| US6369387B1 (en) | 1999-10-15 | 2002-04-09 | Li-Cor, Inc. | Gas analyzer |
| FI116859B (en) * | 2002-09-30 | 2006-03-15 | Noveltech Solutions Ltd | Photoacoustic detector |
| US7664607B2 (en) | 2005-10-04 | 2010-02-16 | Teledyne Technologies Incorporated | Pre-calibrated gas sensor |
| US8785857B2 (en) | 2011-09-23 | 2014-07-22 | Msa Technology, Llc | Infrared sensor with multiple sources for gas measurement |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2648775A (en) * | 1949-04-19 | 1953-08-11 | James L Waters Inc | Method for the analysis of mixtures |
| US3731092A (en) * | 1971-11-11 | 1973-05-01 | Mine Safety Appliances Co | Non-dispersive infrared gas analyzer having sample and reference beams using flow sensitive detector and with unbalanced operation |
| US4008394A (en) * | 1973-06-28 | 1977-02-15 | Sensors, Inc. | Gas analyzing |
| US4013260A (en) * | 1974-09-27 | 1977-03-22 | Andros, Incorporated | Gas analyzer |
-
1980
- 1980-09-19 US US06/188,982 patent/US4355234A/en not_active Expired - Lifetime
-
1981
- 1981-09-09 CA CA000385492A patent/CA1164248A/en not_active Expired
- 1981-09-14 JP JP56144061A patent/JPS5779438A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5779438A (en) | 1982-05-18 |
| US4355234A (en) | 1982-10-19 |
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